United States
                   Environmental Protection
                   Agency
Environmental Monitoring
Systems Laboratory
Cincinnati, Ohio 45268
                   Research and Development
EPA/600/S4-89/012 July 1989
4>EPA         Project  Summary
                   USE PA Method Study 37
                   SW-846  Method  3050
                   Acid  Digestion of Sediments,
                   Sludges,  and Soils
                   Kenneth Edgell
                    An  interlaboratory collaborative
                  study  was conducted  on SW-846
                  Method 3050, "Acid Digestion  of
                  Sediments, Sludges, and Soils,"  to
                  determine  the overall and single-
                  analyst precision estimates for the
                  analyses  of  23  elements   in
                  sediments,  sludges,  and  soils. SW-
                  846 Method 3050 includes quality
                  control, sample preparation, and
                  analysis of  samples by Flame Atomic
                  Absorption (FLAA) and  Graphite
                  Furnace Atomic Absorption (GFAA).
                    The study design was based upon
                  Youden's  non-replicate  plan for
                  collaborative tests  of  analytical
                  methods. Initially, 14 solid wastes
                  were collected, dried, homogenized,
                  and analyzed  by Inductively Coupled
                  Plasma (ICP)  for the 23 metals  of
                  interest. Based  upon these  data,
                  seven  solid wastes were selected
                  that contained naturally occurring
                  elements over  a relatively  wide
                  concentration range. Elements not
                  occurring  naturally were added
                  (spiked) into each solid waste. In the
                  formal study  by  eight laboratories,
                  the solid wastes  were digested with
                  nitric acid  and hydrogen  peroxide,
                  refluxed with  nitric or hydrochloric
                  acid, and analyzed for 21 elements by
                  FLAA and for two elements, arsenic
                  and selenium, by GFAA. The results
                  were analyzed using USEPA  com-
                  puter  programs entitled "Inter-
                  laboratory Method Validation Study
                  (IMVS)." The computer programs
                  produced measures  of overall and
                  single-analyst precision for the 21
elements analyzed by FLAA and for
the two elements analyzed by GFAA.
  The study was conducted by The
Bionetics  Corporation under the
direction of the Quality Assurance
Research  Division,  Environmental
Monitoring  Systems Laboratory, Cin-
cinnati, OH (EMSL-Cincinnati)  under
Contract No. 68-03-3254. Analytical
work was completed in August 1987.
The  study report covers  a period
from January 10, 1987, to February 5,
1988.
   This Project  Summary was
developed  by  EPA's Environmental
Monitoring  Systems Laboratory, Cin-
cinnati, OH, to announce key findings
of the research project that is fully
documented in a separate report  of
the same title (see  Project Report
ordering information at back).

Introduction
  The Hazardous Waste Management
facility permit regulations promulgated in
July  1982  (40 CFR  265)  provide
performance standards for the monitoring
of ground waters, wastewaters, and solid
matrices at  hazardous waste sites. To
facilitate these standards, chemical and
physical analyses are required to  assess
the degree  of  contamination  at and
around the area  of the site. The manual:
7es/ Methods for Evaluating Solid Waste,
Physical and Chemical  Methods, (SW-
846),  November 1986, Third Edition,
provides a unified, up-to-date source  of
information on sampling  and  analyses
related to compliance  with  Resource
Conservation and Recovery Act (RCRA)

-------
regulations.  The success  of these
pollution  control  activities,  particularly
when  legal action  is involved, depends
upon the reliability of the data generated
by  the laboratories;  therefore,  it is
important  to  evaluate the methods
through interlaboratory method validation
studies.
   The Environmental  Monitoring
Systems  Laboratory,  Cincinnati,  OH,
(EMSL-Cincinnati) develops/selects  ana-
lytical  methods and  provides  quality
assurance (QA) support to  agency
programs involving  water  and waste
regulations. In  EMSL-Cincinnati,  the
responsibility for providing  QA support is
assigned  to the  Quality  Assurance
Research  Division  (QARD).  Its  QA
program  is designed  to  establish the
reliability and legal defensibility  of water
and waste data  collected by the Agency,
the state  regulating  authorities,  the
private sector, and  the commercial
laboratories performing compliance ana-
lyses.  One  of  its QA  activities is  to
conduct interlaboratory method validation
studies to evaluate analytical methods
selected for the Agency's operating pro-
grams  such as the Office of Solid Waste.
   This   report  describes  the
interlaboratory  method  validation study
for  SW-846  Method 3050, "Acid Diges-
tion of Sediments, Sludges,  and Soils."
The elements:  aluminum, antimony, bar-
ium, beryllium,  calcium, cadmium, chro-
mium,  cobalt, copper,  iron,  lead,
magnesium,, manganese,  molybdenum,
nickel,  potassium,  silver,  sodium,  thal-
lium, vanadium, and zinc were analyzed
by flame atomic absorption spectroscopy
(FLAA). Arsenic and  selenium were
analyzed  by graphite  furnace  atomic
absorption spectroscopy (GFAA). Origin-
ally, silver and antimony were included in
Method 3050 and  therefore  included in
this study. However, they were removed
from the September 1986 revision of the
method.
   The primary objective  of the study
was to characterize  the behavior  of
Method 3050 in terms of overall precision
and single-analyst precision.  The study
was conducted with  the cooperation of
eight participating laboratories under the
direction  of  the Quality Assurance  Re-
search  Division,  EMSL-Cincinnati.  As
primary contractor to  QARD, The  Bio-
netics  Corporation was  responsible  for
the collection and characterization of the
solid   matrices,  preparation of  user
instructions and report forms, distribution
of samples, and screening of the returned
data for gross errors. The raw data  were
evaluated statistically by the QARD using
a series  of computer  programs  entitled
"Interlaboratory Method  Validation Stud-
ies"  (IMVS).  Upon  review of  the  draft
report by EMSL-Cincinnati, The Bionetics
Corporation prepared the final report.

Description of Study
   The study  design  was based upon
Youden's original non-replicate design for
collaborative evaluation  of  analytical
methods. In this  design, samples  are
prepared in  pairs such that  the  analyte
concentrations of the pairs vary between
5-20% from the mean of the pairs. Seven
sample pairs, one for each solid  matrix,
were  prepared to cover  the  optimum
range of the method as specified  in SW-
846  or in  the concentration  range
naturally occurring in the matrices.

Selection  of Participating
Laboratories
   Twenty-four  commercial laboratories
responded  to  the  abstract in  the
Commerce  Business Daily, inviting
participants  for  the  method validation
study.  Their technical proposals were
evaluated based upon laboratory exper-
ience and   quality  control  practices.
Laboratories  whose  proposals  were
acceptable  were evaluated further  in  a
preaward performance evaluation study.
The  participants selected for the formal
study were  the  eight laboratories with
acceptable  proposals  who  performed
best  in the preaward  study.

Selection  of Solid Waste
Matrices
   Initially, 14 solid waste matrices were
screened for the 23  elements of interest
by ICP analyses and seven solid  wastes
were  selected that  contained  naturally
occurring elements over a relatively wide
concentration range.  These were:

 Solid
Waste             Source
   1   National Bureau  of Standards River
      Sediment, SRM-1645
   2   US EPA, Hazardous Soil QC Sample
      #1
   3   Ethyl Corp., Electroplating Sludge
   4   Marshall Space Flight Center (MSFC),
      Electroplating Sludge
   5   US EPA, Shale I QC Sample WP 386
   6   Varland Metal Service Inc.,
      Electroplating Sludge
   7   EPA Supplied Electroplating Sludge
Aluminum, calcium, iron,  magnesium,
manganese, potassium, and sodium were
present in all seven  samples and did not
require fortification with spiking solution.
Cobalt, molybdenum, thallium, vanac
beryllium, cadmium,  arsenic, selenium,
barium,  silver,  antimony,  chromium,
copper,  lead, nickel, and  zinc did not
occur naturally or were at such low levels
in the solid  wastes that fortification was
required.

Results and Discussion
   The objective  of this study was  to
characterize the performance  of SW-846
Method 3050 in terms of overall precision
and single-analyst precision for 23  trace
metals in sludges, soils, and  sediments.
The IMVS computer programs were used
to summarize the raw data and compile
statistics  for overall standard  deviation,
overall   percent  relative  standard
deviation,   single-analyst  standard
deviation, single-analyst percent relative
standard  deviation, and mean recovery.
Antimony and silver,  which are listed in
Table 1  are not included in the following
discussions because they  are no longer
included in Method 3050.
   The study was intended  to answer two
major questions about  method  per-
formance:
(1)  Does  Method  3050  digestion
    procedure  work equally well on  all
    solid wastes studied?          ^-N
(2)  Do the  matrix effects encounte
    from  any of  the seven solid wasics
    studied prevent establishment  of  a
    linear relationship between precision
    and mean recovery?
   The   following  data  treatment
decisions were  made on  the statistics
generated  by  the  IMVS  computer
programs:
1)  Both overall  and single-analyst pre-
    cision  regression  equations  were
    recalculated after removal of atypical
    solid waste data.
(2)  Weighted linear regression equations
    were not calculated with less  than
    five  sets of  acceptable solid  waste
    data.  In  these  situations  no
    regression equation was  reported,
    and it was  concluded  that the data
    for the  element had a strong matrix
    dependence. The  reader  is referred
    to  Appendix  C,  Statistical
    Summaries, of the full  report, for the
    individual solid  waste  precision
    statistics.
(3)  For  comparison  purposes,   a
    concentration value of five times (5x)
    the  low concentration  limit of the
    range studied was used as the mean
    recovery,  in  the  regression
    equations, to calculate  %RSDs. ?"*
    value is believed to  be  representa*.
    of the reported data in this study.

-------
Rejection of Outliers

   For  the entire study,  the  IMVS
 program rejected 75 data points (2.9%)
 of the 2576 data points submitted. The
 highest number of rejected  points (10)
 occurred for barium while no thallium or
 beryllium data were rejected. Of the eight
 laboratories participating in  the study,
 Laboratory 6 accounted for 25 of the  75
 rejected data points.
 Overall Precision
   The  IMVS computer programs calcu-
 lated the overall precision for each of the
 seven Youden concentration pairs for this
 study.  Utilizing another USEPA computer
 program,  REGRESS, weighted linear
 regression  equations were  fitted to the
 submitted data. These regression equa-
 tions, presented in  Table  1, regressed
 overall precision  (S)   versus mean
 recovery  (X) for  all seven Youden
 concentration pairs (14 data  points).
 Several regression  equations  were
 recalculated after  deletion of solid waste
 data which did  not  show a clear
 relationship to the other solid waste  data.
 The deleted solid  waste  data   are
^identified with each regression equation.
   The mean  %RSD  for  all  FLAA
 elements was 9.4%. Only two of these
 elements, aluminum (22.4%) and potas-
 sium (22.4%), had %RSDs greater  than
 15%, while fifteen elements had %RSDs
 less that 10%. The naturally occurring
 elements:  aluminum,  calcium,   iron,
 magnesium,  manganese,  potassium  and
 sodium, which did not require fortification,
 had a mean %RSD of  11.8%. Cobalt,
 molybdenum, thallium,  and  vanadium,
 which required spiking of all seven  solid
 wastes, had  a mean  %RSD of 8.4%.
 Beryllium, cadmium, chromium, copper,
 lead,  nickel, and zinc  which  were
 evaluated  with a  combination of spiked
 and unspiked solid wastes  had  a mean
 %RSD  of  7.4%.  Based on  the mean
 %RSDs for  these three groups,  the
 overall precision obtained for all elements
 was very  similar  whether naturally
 present or spiked into the solid matrices.
   The  %RSD for the GFAA elements,
 arsenic and  selenium, were 19.7%  and
 29.6%, respectively.
   Barium regression  equations are not
 presented  in Table  1  because   the
 precision data for each of the seven  solid
 wastes  were variable  with  no apparent
^relationship to  mean  recoveries.
Precipitation  reactions forming barium
 sulfate are  suspected  but have not  been
 confirmed.
Single-Analyst Precision

   The  IMVS  computer programs
calculated  the single-analyst  precision
(SR) for each  of  the seven  Youden
concentration  pairs for this study.  The
seven  results for  each element  were
reduced to a single  equation by weighted
linear  regression analysis.  These
regression equations, presented in Table
1, regressed single-analyst precision (SR)
versus  mean  recovery  (X)  and  can  be
used to estimate  the  percent  relative
single-analyst  standard deviation (%RSD-
SR) at any concentration  level in the
range studied.
   The  mean  %RSD-SR for the FLAA
elements was 5.4%  and  ranged  from
cobalt (4.2%)  to aluminum  (8.6%).  The
ratio of the  mean overall  precision,
%RSD, to the mean single-analyst preci-
sion, %RSD-SR, was 1.7:1. The naturally
occurring elements: aluminum,  calcium,
iron, magnesium, manganese, potassium
and sodium had a mean %RSD-SR of
5.8%.  Cobalt,  molybdenum,  thallium and
vanadium which  required spiking of all
seven  solid wastes, had a mean  %RSD-
SR of 5.1%.  Beryllium, cadmium, chro-
mium, copper, lead, nickel, and zinc were
analyzed from a combination of spiked
and unspiked solid wastes and had  a
mean %RSD-SR of 5.2%. Based on the
mean %RSD-SRs for these three groups,
the within-laboratory precision obtained
for all  elements,  whether naturally
present or spiked into the solid matrices,
was very similar.
   The  GFAA elements,  arsenic and
selenium, had %RSD-SRs of 11.4%  and
23.0%  respectively and  were  the only
elements with  %RSD-SRs above 10%.

Conclusions and
Recommendations
   SW-846 Method  3050  is  recom-
mended for the  analyses of aluminum,
barium, beryllium, cadmium, calcium,
chromium,  cobalt,  copper, iron, lead,
magnesium, manganese,  molybdenum,
nickel, potassium, sodium, thallium, vana-
dium,  and  zinc  by  flame  atomic
absorption (FLAA) and for the analyses of
arsenic and selenium by graphite furnace
atomic absorption (GFAA).
   The  linear  regression equations
obtained from  this study and presented in
Table 1 can be used to predict the overall
and single-analyst  precision of Method
3050  for  these elements over  the
concentration range studied
   The  barium precision data obtained
from this study were  variable  with no
apparent relationship to mean  recovery.
Reactions,  perhaps  involving  barium
sulfate  as a precipitate,  are  theorized.
Barium  data  from the  Method  3050
digestion procedure should  be evaluated
relative  to presence of sulfur or  sulfur
oxides in wastes tested.
   Originally, silver and antimony were
included in Method  3050  but  were
removed from the September  1986
revision of the  method.  They  were,
however, included in this study but are
not recommended for  analyses by
Method 3050.

-------
Table 1.      Regression Equations for Overall (S) and Single-analyst (SR) Precision for SW-846 Method 3050
                                                                                    Data Set Corrected for Waste
 Element (Cone Range in ng/gj	Regression Equation3	Waste No. Deleted11	No.c	
Aluminum (715-18700)

Antimony (63-1700)

Beryllium (5.5-231)

Cadmium (5.6-154)

Calcium (11900-185000)

Chromium (67-97700)

Cobalt (91-624)

Copper (66-25800)

Iron (16900-123400)

Lead (715-20800)

Magnesium (2050-50700)

Manganese (287-1100)

Molybdenum (180-5600)

Nickel (22-75000)

Potassium (448-4100)

Sodium (227-105700)

Thallium (129-2400)

Vanadium (334-7420)

Zinc (93-188900)

Arsenic" (21-616)

Selenium* (3.98-105)

Barium* (123-11630)

Silver* (37-344)
         S=0.210X + 51.0
        SR=0.0742X + 41.2
        S=0.145X +  10.58
       SR=0.0310X + 16.35
        S=0.0676X + 0.37
        SR=0.0411X * 0.26
        S=0.0437X + 0.78
        SR=0.0446X + 0.41
          S=0.0893X- 66
        SR=0.0662X -881
        S=0.0923X + 0.73
        SR=0.0564X + 0.66
        S=0.0525X + 7.22
        SR=0.0428X -0.40
         S=0.0636X + 0.0
        SR=0.0460X  + 2.0
        S=0.0522X + 693
        SR=0.0364X + 162
         S=0.0607X - 17.4
        SR= 0.0292 X  + 4.3
        S=0.0572X + 106
        SR = 0.0408X  + 26
         S=0.0840X -3.0
        SR = 0.061 8X- 6.2
         S=0.0739X -3.5
        SR=0.0936X-10.8
                                                          4 A 43
 S=0.0678X
Sfl=0.0437X
                     6.44
                      5.64
         S=0.796X + 61.8
       SR=0.0739X + 16.1
        S=0.0646X + 26.4
        SR=0.0481X + 8.4
         S=0.0559X + 7.5
        SR=0.0213X + 4.3
          S=0.133X -4.2
       SR=0.0437X -i- 13.6
        S=0.0832X + 1.10
       SR=0.0639X + 1.33
         S=0.188X + 0.98
       SR=0.0857X + 2.95
         S=0.192X * 2.06
        Sfl=0.787X + 0.85
 No equation developed. See App. C
in main report for individual statistics.
 No equation developed. See App. C
in main report for individual statistics.
                                   1,7
                                   1,7
                                   6,7
                                   6,7
                                    7
                                    7
                                    6
                                    6
                                    6
                                    6
                                   2,5
                                   2,5
         1A, 1B, 2B

             5B
                                                            7B
All data sets corrected except
           5A.5B
         2A, 28, 78
                                                            6B



                                                      5A, 6A, 7A,7B

                                                  All data sets corrected
a Weighted least squares technique.
b Indicates the waste deleted to arrive at the regression equation presented.
c Solid waste data set that was corrected for errant data points. See Section 5, Results and Discussion, for further details in
 main report.
d Analyzed by graphite furnace atomic absorption (GFAA). All other analyses by flame atomic absorption (FLAA).
e The individual data sets were too variable to fit a linear relationship; thus, no equations were developed.

-------
   Kenneth Edgell is with The Bionetics Corporation, Cincinnati, OH 45246
   Edward L Berg is the EPA Project Officer (see below).
   The complete report, entitled  "USEPA Method Study 37, SW-846 Method 3050
         Acid Digestion of Sediments, Sludges, and Soils," (Order No. PB 89-181
         9521 AS; Cost: $21.95, subject to change) will be available only from:
             National Technical Information Service
             5285 Port Royal Road
             Springfield, VA22161
             Telephone: 703-487-4650
   The EPA Project  Officer can be contacted at:
             Environmental Monitoring Systems Laboratory
             U.S. Environmental Protection Agency
             Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
      BULK RATE
POSTAGE & FEES PAID
         EPA
   PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/600/S4-89/012

-------